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Патент USA US3050426

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?iga
United States atent ,
1
3,650,419
Patented Aug. 21, 1962
2
hardening, is hardly suitable for wet ?xing in the presence
3,056,419
of water.
PROCESS FOR FHING AMINOPLASTS IN THE
WET STATE 0N CELLULOSIC FEROUS MA
TERIALS
‘
.
_
_ Since in almost- all cases the addition of a catalyst leads
to a very undesirable reduction in the stability of the
’
impregnating solution, it is usually recommended to add
Andreas Ruperti, Arlesheim, Switzerland, assignor to
I
Ciba Limited, Basel, Switzerland
No'Drawin'g. Filed Apr. 29, 1957, Ser. No. 655,515
Claims priority, application Switzerland May 8, 1956
2 Claims. (Cl. 117-1385)
the catalyst immediately before the solution is to be used.
Hitherto dry hardening has chie?y been used in the tex
tile industry. Dressings of arti?cial resin have been ap-.
plied to fabrics almost exclusively by impregnation on
10 a ioulard.
For the improvement of textiles and other ?brous ma
For this purpose a bath stability of a few
hours su?ices, because the impregnating bath is rapidly
terials with aminoplasts it is customary to impregnate the
consumed or is continually renewed. Recently the ad
vantages of wet ?xing having been recognized for certain
condensation product and then dry the material. Since
purposes. Thus, for example, cotton yarn to be used for
drying alone is generally insul?cient to produce the de 15 the manufacture of ?shing nets has been given a rot-proof
sired eitect, the material is subsequently subjected to a
dressing with melamine resin by wet ?xing, for ‘which
raised temperature in order to harden the condensation
purpose dry hardening is unsuitable. in contradistinction
product. By hardening in the dry state there are formed
to the impregnation of fabrics followed by dry hardening,
material with an aqueous solution of an amine-aldehyde
water-insoluble products and at the same time the prop
it is desirable to carry out wet ?xing in many cases with '
erties of the impregnated ?bers undergo substantial 20 yarn or loose ?bers in dyeing apparatus and at a very
change. The reduction in the capacity of the ?bers for
high liquor ratio. Such applications in long liquors can
absorbing water and in their swelling capacity results in
only be carried out economically if the impregnating baths
better retention in shape, crease resistance and other im
provements of the‘material. At the same time the ca
are sut?ciently stable and can be repeatedly used over ‘a
long period. The decisive importance of bath stability
pacity of the ?bers for being dyed with direct dyestuffs is 25 necessitates the use for wet ?xing of catalysts which ful-l
reduced or completely eliminated. The mechanical prop
?ll requirements that have not to be taken into account in
the case of catalysts used for dry hardening. Only in
exceptional cases can acid baths be used for wet ?xing,
erties, such as tensile strength in the wet‘ and dry state,
are more or less strongly impaired, especially in the case
owing to the continual change in the impregnating solu
Instead of hardening the aminoplast in the dry state, 30 tion. It is possible to use potentially acid salts as cata
it can be converted on the ?ber into the insoluble state
~lysts, which depend for their actionupon reaction with
of materials of natural cellulose ?bers.
without previous drying and without completely remov
formaldehyde, but these catalysts also are hardly ‘suitable
for operation in standing baths which involve keeping
ing the water derived from the impregnating solution,
and retained by the ?ber, before completion of the con
the impregnating solution for more than one working day.
densation of the resin, so that'the condensation takes 35 The catalysts ‘of the third group mentioned above, which
place in the presence at water derived from the impreg
depend for their action on the formation of complex acids
during drying or upon thermal decomposition of the an
nating solution. In this method of ?xing, which is called
hydrous catalyst during dry hardening, are by their very
wet ?xing in order to distinguish it from dry hardening,
the reaction takes quite a different course. The reactions
nature and function unsuitable for Wet ?xing where
causing reduction in swelling capacity are suppressed by 40 there is no previous drying. Accordingly, new principles
the presence of water and the aminoplast becomes insolu
must be sought which lie outside those hitherto known
for dry hardening.
'
'
ble without the properties of the ?ber being changed in
the way they are by dry hardening. The capacity of the
The present invention is based on the observation that
?ber for being dyed with direct dyestuffs isnot changed,
substances which are stable in the anhydrous state, do not
themselves produce an acid reaction when added to the.
the mechanical properties of the ?ber are not impaired,
the ?bers are protected against the attack of micro
resin solution, and change slowly in aqueous solution at
room temperature, but are hydrolyzed by water at a raised
temperature with the splitting oil of acid or a substance
of acid reaction, ful?l to a very great extent the require-4
ments for catalysts for wet ?xing.
organisms, and yet such improvements as lead to a reduc
tion in the capacity for absorbing water or in the swelling
capacity are still achieved. Accordingly, fundamental
di?erences both with regard to the course of reaction and
the effects produced occur depending on whether dry
hardening or Wet ?xing is used.
Both dry hardening and wet ?xing proceed more rap
idly the lower the pH value, so that in order to accelerate
the condensation an acid or potentially acid substance is
, Accordingly, the present invention provides a process
for ?xing 'aminoplasts in the wet state on ?brous materials
at a raised temperature, wherein there is used as catalyst
a compound having the properties given above. Especial
' 1y suitable are esters of polyhydric alcohols or of polybasic
' used as catalyst.
Under. acid conditions the aminoplast undergoes slow
condensation in the impregnating solution, so that the
composition of the solution does not remain constant.
acids, of which the solubility in water is sui?cient to enable
them to dissolve at the required concentration in the
aminoplast bath. As such esters there may be mentioned,
It is therefore customary to use a potentially acid salt 60
for example, diacetin, monochlorhydrin, dichlorhydrin,v
glycol diacetate, glycol methyl ether acetate, glycol ethyl
as catalyst, which produces an'acid reaction during the
ether acetate and diethyl tartrate.
hardening by reaction with formaldehyde. However, the
same reaction proceeds, although more slowly, in the
generally not suitable for dry hardening, because their.
action depends on their undergoing hydrolysis by the'
water present during ?xing at a raised temperature, and.
These catalysts are
impregnating solution so that the latter retains its usable
condition for a relatively short time. The most stable 65 they are unable to produce the necessary lowering in pH
baths are obtained by using catalysts which are neither
value during dry hardening.
acid nor react with formaldehyde to form substances of
The term “hardenable aminoplasts,” which products
acid reaction, and which produce an acid reaction only
can be used in the impregnating process, is used herein to
during the concentration which occurs during drying,
include hardenable carbamide or melamine resins, which
either due to .the formation of strong complex acid or 70 are either soluble in Water or of limited solubility in Water,
due to thermal decomposition. The latter type of cata
and may be etheri?ed, and which are obtainable in known
lysts, which can be successfully used in the ordinary dry
manner by condensing formaldehyde with such com
3,050,419
3
pounds as, for example, urea, thiourea, cyanamide, di
cyandiamide, biguanide, melamine, formoguanamine, ace
toguanamine or the like, and also mixtures of two or more
of these compounds, and also their alkyl- or acyl-com
pounds. Especially good results are obtained with water
soluble condensation products of melamine and formalde
hyde.
.
.
4
.
.
material, for example, loose ?brous material, yarn, fabric
or knitted goods. The cellulose ?bers to be treated by
the process of this invention may be composed of natural,
mercerized or regenerated cellulose.
.
The following examples illustrate the invention:
Example 1
As condensation products of limited solubility in water
Three'hank-s of cotton yarn weighing 10 grams each
there are tov be understood those colloidal intermediate
were impregnated with a solution containing, per liter,
stages of condensation which result immediately the con
densation is continued beyond the crystalline methylol
‘stage. Accordingly, they possess the characteristic of
being precipitated from concentrated aqueous solutions by
the addition of water.
The condensation products of unlimited solubility in
water are used in’ the form of aqueous solutions, and those
of limited solubility in‘ water are advantageously used in
the form of dispersions.
The impregnating bath advantageously contains about '
5-15% of the aminoplast either in solution or in disper- -
sion. The impregnation is advantageously carried out by
applying the aminoplast to the ?ber in a proportion
amounting to about 4-10% on the weight of the ?ber, but
higher or lower proportions may be applied. Generally
speaking, the proportion of catalyst is 5-10% on the
100 grams of a melamine-formaldehyde condensation
product of unlimited solubility in water obtained ‘from
one molecular proportion of melamine and about 2 mo
lecular proportions of formaldehyde, and 5 grams of di
chlorhydrin, and each ‘hank was centrifuged in a per
forated metal beaker in a lalboratory centrifuge. I One
of the hanks was then dried and subjected to hardening.
for 6 minutes at 140° C. (hank No. 1). The other two
hanks were subjected to wet ?xing without being dried,
hank'No. 2 being maintained overnight in a closed glass, i.
tube at 80° C. in a thermostatic cabinet, and hank No. 3;
being heated for one hour at 130° C. in an autoclave.
In order to prevent local drying at the places of contact
with the vessel walls, the hanks were protected during
the wet ?xing by winding round them strips of wet ma- i
terial that had been impregnated together with the hanks.
weight of the arninoplast used.
The degree of ?xation of resin was determined by analy
sis for nitrogen before and after boiling the'treated ma
The impregnating solution, when ready for use and con
taining the catalyst, is advantageously prepared so as to
terial in distilled water for 1/2 hour. The values for
have a weakly alkaline pH value, and for this purpose no
nitrogen and the amounts of resin ?xed fast to boiling
special addition is normally required when an aminoplast 30 (calculated fromthe nitrogen values), are given in the
ofv weakly alkaline reaction and a neutral catalyst are
following table:
7 used. At such a pH value the baths can be kept for many
days. As, however, even at room temperature slow hy
drolysis of the catalyst occurs in aqueous solution, the
alkalinity of the bath gradually diminishes in the course of
time. It is therefore of advantage to take care that the I
pH value does not fall below 7.2, because at this point,
which is still on the alkaline side, the stability of the bath
rapidly diminishes so that it becomes unusable in a short
time. By the addition of a small amount of sodium car
bonate or other alkaline compound the reduction in pH
value which occurs after several hours or days can easily '
be'corrected, At the same time, however, it is necessary
to add a quantity of fresh catalyst equivalent to the addi
tion of alkali in order to maintain the full activity of the 4:5
catalyst. "In this manner an impregnating bath can be
'used for a very ‘long time; Furthermore, concentrated
treatment baths may be used, such as are customary.
The impregnation may be carried out by the customary ,
methods and with the usual types of apparatus.
Percent Nitrogen on
the ?bre
Hank No.
Amount of
resin ?xed
fast to
boiling,
before
drying
5. 3
after boiling
hour
percent
‘
0. l'
5. 0
4. 9
4. 5
4. 5
2
98 '
100
By using monochlorhydrin, diacetin, glycol ethyl ether
acetate or glycol methyl ether acetate, instead of dichlon,
hydrin,there are obtained by the same procedure entirely
analogous results. In all cases as the result of, wet ?xing
the amount of resin?xed fast to boiling exceeded 90%,‘
whereas 'in dry hardening practically no resin was‘ ?xed
fast to boiling.
V Inorder to test bath stability somewhat concentrated .
;' The ?xation of the aminoplast is advantageously carried
solutions containing, per liter, 120 grams of the same
out entirely without drying the impregnated ?brous mate- ‘
melamine-formaldehyde condensation, product and 6
rial. Partial drying of the material before or ‘(luring the
grams of the aforesaid catalysts, were allowed to stand at,
room temperatu-refor a long time. The change in hy
?xation is permissible, provided that the partial drying is
uniform and not accompanied by harmful migration of
drogen-ion concentration of the solutions containing cata
the condensation product. The simplest Way of carrying
lyst was observed by means of theionoscoperof the Swiss
out the process is to squeeze or centrifuge the‘ ?brous ma;
Vaccinationand Serum-Institute until the original pH
valueofj7l8ito 8.0 had fallen to 7.2; This is the critical
point at which, it is necessary to add an alkaline sub
say, torernove' the excess of bath liquor mechanically,
without drying the material, and then to maintain the 60 stance, otherwise the properties of the bath change rapidly,
material at a raisedtemperature for a prolonged period
which becomes evident 'by the solution gradually becom
‘ ing turbid and then llocculating or gelatinising. The bath.
during 'which premature drying is prevented. The period
underwent no 'visible change until the critical pH of 7.2.
fonwhich it"is necessary to maintain the material at a
had been reached in the case of mono- and di-chlorhydrin
raised temperature is dependent, on the one hand, on the;
nature of the aminoplast and reaction accelerator used 65 in 3 days, diacetin in 4-days and in the caserof the other
and, on the other, on the temperature. The temperature is . two catalystsin 5 days. »
so chosen that the catalyst undergoes hydrolysis su?iciene,
Example 2
terial impregnated with a solution or emulsion, that is to ’
ly rapidly. :It is of advantage tomaintain the impreg
nated ?brous material in' a closed vessel, whereby prema
To an aqueous solution containing, per liter,,110 grams .
tu're drying is automatically prevented. It is also very 70 of a melamine-formaldehyde condensation product of un
limited solubility in water obtained from 1 molecular
advantageous-to use direct steam, if desired, under pres
proportion of melamine and about 2 molecular propor
sure, as'the source of heat.
.
'
vThe impregnation ofvthe cellulose ?brous material with .
tions of formaldehyde, were added 5.5 grams of diacetin
the aminoplast followed by wet?xing can be carried out
per liter as catalyst andl gram of a non-ionic Wetting
at any desired stage in themanufacture of the ?brous 75 agent per liter. The solution was used to impart a rot~
lu.
3,050,419
5
6
resistant dressing to cotton yarn, which was impregnated
in a dyeing apparatus in the form of cross-Wound bob
the impregnating liquid, the said hardening catalyst being
bins, then centrifuged and, without being dried, sub
acetin, monochlorhydrin, dichlorhydrin, glycol diacetate,
jected to wet ?xing by treatment with steam at 130° C.
for 11/2 hours in a pressure boiler.
glycol methyl ether acetate, glycol ethyl ether acetate
By the subsequent addition of ‘a solution containing,
per liter, 135 grams of the same melamine-formaldehyde
condensation product, 5.5 grams of diacetin and 1 gram
2. In a process for imparting to cellulosic ?brous ma
terial a water resistant impregnation protecting such ma
of wetting agent, the consumption of impregnating liquor
and the fall in concentration due to a certain substantivity
were compensated, ‘and the impregnating solution was
repeatedly used for treating further quantities of yarn.
At the end of the working day the impregnating solution
a compound selected from the group consisting of di
and diethyl tartrate.
terial from attack by micro-organisms, Without substan
tial change in the tensile strength of the said material, by
treating it with an aqueous impregnating liquid of an
aminoplast which contains a hardening catalyst, wherein
after impregnating the material and removing mechani
cally the excess of impregnating liquid the aminoplast is
hardened in and upon the ?ber into the water-insoluble
was placed in a storage container and stabilized by the
addition of 3.3 grams of sodium carbonate per liter. 15 condition, the improvement consisting of heating the im
pregnated material to e?ect said hardening with retention
When the impregnations were repeated a few days later
of a substantial amount of the water of the impregnating
the same impregnating solution was used, after adding
liquid until the resin condensation is completed, so that
5.5 grams of fresh diacetin, per liter, thereof.
the condensation into the water-insoluble state is actually
All the impregnations were satisfactorily ?xed when
conducted in the presence of water originating from the
subjected to the boiling test, so that the rot-resistant
dressing was completely Water-resistant.
What is claimed is:
1. In a process for imparting to cellulosic ?brous ma
terial a water resistant impregnation protecting such ma- '
terial from attack by micro-organisms, Without substan
tial change in the tensile strength of the said material, by
treating it with an aqueous impregnating liquid of an I
‘aminoplast which contains a hardening catalyst, wherein
after impregnating the material and removing mechani~
vcally the excess of impregnating liquid the aminoplast 30
is hardened in and upon the ?ber into the water-insoluble
condition, the improvement consisting of heating the im
gpregnated material to effect said hardening with retention
of a substantial amount of the water of the impregnating
liquid until the resin condensation is completed so that 35
the condensation into the water-insoluble state is actual
ly conducted in the presence of water originating from
impregnating liquid, the said hardening catalyst being
diacetin.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,417,014
Pollard _____________ _._. Mar. 4, 1947
2,484,598
2,555,277
Weisberg et a1. _'_. ______ __ Oct. 11, 1949
Roger ______________ __ May 29, 1951
2,559,349
2,709,141
2,762,719
2,763,574
Detwiler ______________ __ July 3,
Burks _______________ __ May 24,
Kleiner _____________ __ Sept. 11,
Ruperti ____________ __ Sept. 18,
1951
1955
1956
1956
2,819,179
Barnard __:_ ___________ __ Jan. 7, 1958
2,859,136
Marsh et a1. _____ ________ Nov. 4, 1958
526,449
Canada ______________ __ June 19, 1956
FOREIGN PATENTS
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